It's January 2021 and Rick Deckard is a bounty hunter for the San Francisco
Police Department. He hunts down and "retires" rogue androids (andys).
Thanks to technology from companies like the Rosen Association, it's getting
increasingly hard to tell the androids from the humans, but there is an
empathy test that Deckard can administer; androids don't feel empathy for
humans or for each other. Meanwhile, due to the devastation wreaked
by nuclear fallout from World War Terminus, animal life is nearly sacred
and pets are status symbols. Deckard and his wife have an electric
sheep just to try and keep up with the Joneses. Also, the fallout
is starting to impact the genetics and fertility of humans, so the government
is advocating emigration to Mars, running a Public Service Ad that warns:
"Emigrate or degenerate! The choice is yours!" Amidst
all of this, a new religion has arisen called Mercerism. It's founder,
Wilber Mercer, is an empath who is taking all of mankind's suffering upon
his own shoulders. Adherents transmit their pain to him through Mercer
Boxes and receive inner peace in return. Now Deckard has been given
the assignment of retiring a gang of 8 andys and, to his own horror, he
finds that he is starting to develop feelings of empathy for these humanoids
while Mercer is telling him that it's wrong to kill the androids, but that
he has to go ahead and do it anyway.

This is my favorite of Philip K. Dick's novels. It deals imaginatively
with the big themes that are central to speculative fiction, especially
what is it that makes us human. And, unlike some of his other books,
he maintains the momentum of the basic story line throughout and keeps
everything reasonably coherent.